[On the morphology of Syphacia callosciuri n. sp., pin-worm parasite of a Malaysian squirrel and on the origin of Rattus pin-worm, Syphacia muris (Yamaguti, 1935) (author's transl)].

Description of a new species of Oxyurid: Syphacia (Syphatineria) callosciuri n. sp. parasite of a Sciurid rodent Callosciuris caniceps in Malaysia. In rodents belonging to the genus Callosciurus in Malaysia two species: S callosciuri n. sp. and S. owyangi Quentin, 1975, show morphological characteristics which are intermediate between the primitive Syphacia and two different lines of species parasite of recent rodents. These observations appear to indicate that the adaptation of Syphacia of Sciurids to the modern rodents has occured in South-East Asia.